New Satellite Will Improve Weather, Climate, Ocean Forecasts

The mission is expected to return a vast amount of new data that will allow greater precision in weather, climate and ocean forecasts.

Jason-2, or the Ocean Surface Topography Mission, is a joint venture between NASA's Jet Propulsion Laboratory, the U.S. National Oceanic and Atmospheric Administration, the French Space Agency, and the European Meteorology Satellite service.

"Sea-level measurements from space have come of age," said Michael Freilich, director of the Earth Science Division in NASA's Science Mission Directorate, Washington. "Precision measurements from this mission will improve our knowledge of global and regional sea-level changes and enable more accurate weather, ocean and climate forecasts."

With an orbit 1,336 kilometers (830 miles) above the Earth's surface, Jason-2 will be one of two satellites that will fly in tandem, all equipped with special altimetry sensors to precisely measure sea level, and indirectly infer ocean heat content changes.

The satellite will provide 95 percent coverage of the world's ice-free oceans, repeating its coverage every 10 days and measuring sea surface height with an accuracy of about three centimeters (1.3 inches).

Measurements of sea-surface height, or ocean surface topography, reveal the speed and direction of ocean currents and tell scientists how much of the Sun's energy is stored by the ocean. Combining ocean current and heat storage data is key to understanding global climate variations.

"OSTM/Jason 2 will help create the first multi-decadal global record for understanding the vital roles of the ocean in climate change," said project scientist Lee-Lueng Fu of NASA's Jet Propulsion Laboratory in Pasadena. "Data from the new mission will allow us to continue monitoring global sea-level change, a field of study where current predictive models have a large degree of uncertainty."

An artist concept shows the Ocean Surface Topography Mission instruments as they fly on the Jason-2 spacecraft to measure the height of oceans and the waves. (Image courtesy NASA)

The mission will extend into the next decade the continuous record of sea-surface height measurements started in 1992 by the NASA-French Space Agency's TOPEX/Poseidon mission and extended by the NASA-French Space Agency Jason 1 mission in 2001.

OSTM/Jason 2 will use its thrusters to raise itself into the same orbital altitude as Jason 1 and move in close behind its predecessor. The two spacecraft will fly in formation, making nearly simultaneous measurements.

For six to nine months after launch, scientists will verify the instruments are calibrated precisely. OSTM/Jason 2 then will continue Jason 1's former flight path, and Jason 1 will move into a parallel ground track midway between two of the OSTM/Jason 2 ground tracks.

This tandem mission will double the amount of data collected, further improving tide models in coastal and shallow seas and helping researchers better understand ocean currents and eddies.

Other countries too are depending on the information the satellite will send back to Earth to develop their own scientific programs.

"There's plenty resting on this satellite in terms of where our ocean and climate science is going," says Dr. David Griffin, an Australian oceanographer from the government's CSIRO Wealth from Oceans National Research Flagship and a member of the international science team which advises on satellite altimeter missions.

He says the ocean satellite is critical to Australian science. "Jason-2 provides a lifeline between space and some very significant science projects that are integral to our capabilities in understanding how the oceans are changing and particularly future ocean forecasting products," Griffin said Friday.

This information is also important for: Australia's evolving ocean forecasting system, BLUElink; sea safety and offshore oil and gas operations; measuring global sea level rise; tracking large-scale ocean-atmosphere phenomena like El Niño and La Niña and marine mammals feeding in nutrient-rich ocean eddies; and forecasting currents for sports events such as the Sydney-Hobart yacht race.

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